The invention relates to the field of chambers and devices for extinguishing electric arcs.
Circuit breaker devices for low voltages (U_AC≤1000 volts (V) and U_DC≤1500V), generally enable an electric arc to be extinguished in air. The advantage of this technique compared with extinguishing the arc in a vacuum, in sulfur hexafluoride (SF6), or in oil, or indeed compared with devices making use of an insulated gate bipolar transistor (IGBT), lies in being simple to fabricate and use, and consequently in being of low cost.
Breaking current on a direct current (DC) electricity network necessarily involves generating a back electromotive force (emf) of potential that is greater than the potential of the source to be interrupted. This is the major difficulty for breaking DC. In the context of techniques for breaking in air, the electric arc generated when opening the switch in air is used as means for generating a back emf.
The main techniques of breaking in air are discussed below.
The arc lengthening technique serves to lengthen and thus cool the arc while opening the switch. Nevertheless, this principle can be found to have poor performance on overload.
The technique of lengthening and splitting the arc combines lengthening the arc with splitting it in an extinction chamber. Depending on the current to be broken, it is possible that splitting might not come into effect and there can exist critical levels of current for which the arc stagnates at the inlet to the chamber. This principle has the advantage of behaving well on overload since the splitter plates support the arc and enable it to be cooled effectively.
The technique of lengthening by magnetic blowout uses a permanent magnet that tends to blow the arc out magnetically. Such magnetic blowout lengthens the arc to a great extent and cools it effectively. Nevertheless, this extinction principle can be limited at high currents since the cooling of the arc can be degraded as a result of lengthening being less effective at such a level of current.
Furthermore, and by way of example, extinction can be made more difficult in the field of photovoltaic (PV) installations because the panels being used deliver voltages that increase from year to year in order to reduce the costs of such installations. In the content of such applications, it is known to connect a plurality of switches in series in order to increase the breaking capacity of the resulting device. Nevertheless, that solution is not entirely satisfactory.
Other applications, e.g. in the railway field, can also require the use of devices having considerable breaking capacity on a DC network so as to enable overload voltages to be broken.
It is thus desirable to improve existing electric arc extinction devices by improving their arc extinction capacity. It is also desirable to obtain circuit breaker devices that can be used for splitting an electric arc generated after passing a direct current or an alternating current between electrical contacts.
There thus exists a need to have novel extinction chambers and novel breaker devices presenting improved circuit-breaking capacity.
There also exists a need to have novel breaker devices suitable for facilitating penetration of an electric arc into the depth of the extinction chamber.
There also exists a need to have novel breaker devices and novel extinction chambers capable of splitting an electric arc after a direct current or an alternating current has been flowing between electrical contacts.